JPS6011213B2 - fuel supply device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel supply system for a fuel injection type internal combustion engine, and more particularly to a type of fuel supply system in which an air valve is provided upstream of a throttle valve in an intake pipe.

This air valve is provided to set the intake pressure in the intake pipe to a predetermined value relative to atmospheric pressure, and to make the amount of air taken into the intake pipe proportional to the opening degree of the air valve.

In this type of fuel supply system, fuel metering is performed by a fuel metering device that is associated with an air valve.

This fuel metering device has a built-in metering orifice. The fuel metering device controls the opening of the metering orifice in proportion to the opening of the air valve. Fuel is sent from the fuel tank to the fuel metering device via the fuel pump.
The amount is measured according to the opening degree of the built-in metering orifice.

Therefore, if the pressure difference through the fuel metering device, more precisely, the pressure difference across the metering orifice, is always kept constant, the fuel is metered to a value proportional to the opening degree of the metering orifice. That is, since the degree of opening of the air valve and the opening degree of the fuel metering device are proportional, fuel is measured in proportion to the degree of relationship of the air valve. A constant differential pressure valve is provided to maintain the pressure differential across the fuel metering device at a predetermined value.

Constant differential pressure valves in conventional fuel supply systems variably throttle the fuel on the wake side (i.e., metered fuel) in response to the pressure difference between the upstream and downstream sides of the fuel metering device. The back pressure on the outlet side is controlled to maintain the pressure difference at a predetermined value. However, this constant differential pressure valve of conventional fuel supply systems has drawbacks.

That is, in order to throttle all of the metered amount supplied to the internal combustion engine in response to the pressure difference, a constant differential pressure valve with a relatively large capacity is required. Usually, this constant differential pressure valve uses a diaphragm type constant differential pressure valve, that is, the pressure difference is sensed by the diaphragm, and the diaphragm changes the gap between the nozzle tip installed opposite the diaphragm. It has become. Since the metered fuel is injected through this nozzle via an injector into the intake pipe, the diameter of the nozzle must be large enough to flow the maximum fuel flow consumed by the internal combustion engine. If the nozzle diameter becomes large, highly accurate and responsive operation cannot be expected for throttle control of metered fuel, which is performed by changing the gap between the nozzle and the diaphragm. Furthermore, in order to allow the maximum flow rate even in this gap, the value of the maximum gap is increased so that the range of movement of the diaphragm from the minimum gap to the maximum gap with respect to the nozzle is increased. In order for the diaphragm to move smoothly over this wide range of movement, the diaphragm must be large in size. Increasing the diameter of the diaphragm improves control accuracy, but ``inevitably there is a delay in operation, the hunting phenomenon increases, and excessive response controllability is observed.Furthermore, if the lift amount of the diaphragm becomes excessive, The diaphragm becomes permanently strained, resulting in accuracy errors and lack of reliability.In order to reduce the capacity of this constant differential pressure valve, a constant differential pressure valve is provided for each engine cylinder chamber of an internal combustion engine. has been put into practical use, but for this purpose it is necessary to provide as many constant differential pressure valves and fuel injection devices or fuel discharge devices as there are engine cylinders, which increases the number of parts and causes high costs.

The present invention aims to provide a fuel supply device that solves the above-mentioned drawbacks. According to the present invention, most of the metered fuel from the fuel metering device is sent directly to the injector and is not throttled by the diaphragm and nozzle of the constant differential pressure valve.

That is, the metered fuel preferably flows so as to bypass the constant differential pressure valve, and a portion of the metered fuel is introduced into the constant differential pressure valve to the extent that the metered fuel pressure can be sensed by the diaphragm. . In detail, the fuel supply device according to the present invention includes an intake pipe, a throttle valve provided in the intake pipe, an air valve provided in the intake pipe upstream of the throttle valve, and a fuel metering valve that moves on the air valve. a device;
A fuel supply device that supplies fuel at a predetermined pressure of the fuel metering device, a fuel tank that holds the supplied fuel, a constant differential pressure valve device that maintains the pressure difference through the fuel metering device at a predetermined value, and a fuel metering device. A diaphragm valve device in which a constant differential pressure valve device detects and amplifies fluctuations in pressure difference via the fuel metering device; Due to the fluctuations in the pressure difference detected and amplified by the valve device, the diaphragm valve device has a variable throttle device installed in the injector, and the diaphragm valve device only has the function of detecting the fluctuations in the pressure difference of the fuel metering device. It is characterized by controlling the pressure of the metered fuel by throttling the metered fuel by a variable throttle device, that is, at the stage of discharge from the injector, to change the flow resistance. It is something to do.

According to a preferred embodiment of the invention, the diaphragm valve device has a first chamber for introducing metered fuel from the downstream side of the fuel metering device and a second chamber for introducing the supplied fuel from the upstream side of said fuel metering device. The first chamber and the second chamber are divided by a diaphragm, the diaphragm is biased toward the second chamber by a spring provided in the first chamber, and the second chamber has an inlet opposite to the diaphragm. A nozzle is provided having a disposed tip and a disposed rear end of a fuel discharge boat such that fuel discharged from the discharge boat is returned to the fuel tank through a fixed restriction and configured to provide a fuel metering device. If the pressure difference across the nozzle fluctuates, the diaphragm changes the gap between it and the nozzle tip, changing the flow rate of fuel flowing from the nozzle inlet to the discharge boat, resulting in large fluctuations in the fuel pressure upstream of the fixed throttle. It becomes like this. The variable throttle device responds to this fluctuation in fuel pressure, changes the variable throttle opening, changes the resistance to the flow of metered fuel, gives pressure fluctuations to this metered fuel, and controls the pressure difference to be constant. .
Further, according to a preferred embodiment of the present invention, the variable throttle device in the injector has a metering fuel chamber for introducing metered fuel and a pilot chamber for introducing exhaust fuel from the fixed throttle upstream side of the boat in room 9E. , has a movable piston that partitions a metering fuel chamber and a pilot chamber, and a piston rod that is integrally provided with the movable piston and operates a variable throttle,
The metering fuel chamber and the pilot chamber are each provided with a spring that biases the piston in opposite directions.

The diaphragm valve device and variable throttle device described above constitute a feedback circuit.

Since the present invention has a feedback circuit, the pressure difference before and after the fuel metering device can be accurately maintained at a predetermined value, and the diaphragm valve device can have a low capacity, making it possible to have a compact structure. .

Furthermore, according to a preferred embodiment of the invention, the injector has a fuel discharge chamber having a nozzle opening opening into the intake pipe, the discharge chamber being a cylindrical chamber, and The fuel boat that discharges metered fuel in the tangential direction closes, and the fuel boat and the tip of the piston rod of the variable throttle device work together to form a variable throttle, and the metered fuel is discharged from the fuel boat into the fuel discharge chamber and rotates. The given fuel is designed to promote atomization.

Furthermore, according to a preferred embodiment of the present invention, an air swirl chamber is provided so as to surround the nozzle opening □ of the fuel discharge chamber of the injector, and the fuel to be rotated and discharged from the nozzle closing is transferred to the intake air flow from the air swirl chamber. The injector is further rotated to further promote atomization.

Hereinafter, the present invention will be explained in detail in the form of an embodiment and with reference to the accompanying drawings.

FIG. 1 shows a fuel supply system for an internal combustion engine showing a first embodiment of the present invention.

In the figure, reference numeral 1 denotes an intake pipe of an internal combustion engine (not shown), into which intake air is introduced through an effect cleaner (not shown) by the suction action of the internal combustion engine.

In this embodiment, a piston-type throttle valve is used, but a butterfly-equipped throttle valve may also be used. A piston 4 protrudes into the intake pipe 1 through a closed opening 5a provided in the intake pipe 1. The piston 4 is slidable relative to the suction tube 1, and the cylindrical housing 4
The throttle valve is deflected to the cut-off position by a spring 5 provided in the throttle valve cut-off position. A piston shaft 4b is coaxially provided on the piston 4, and the left end of the piston shaft 4b penetrates the bottom of the cylindrical housing 4a and protrudes outward, and a link mechanism for the driver's accelerator pedal ( (not shown) are connected. An air valve 3 is provided in the intake pipe 1 upstream of the piston type throttle valve. vinegar. The piston 4 of the tutle valve opens and closes the intake pipe 1 by operating the accelerator pedal, thereby controlling the amount of air taken into the intake pipe 1. The air valve 3 operates according to the amount of intake air, and rotates in the opening direction when the amount of intake air increases. The pressure in the air pressure chamber 6 defined between the air valve 3 and the throttle valve piston 4 is controlled to be constant during steady operation. A feedback control device is provided for this purpose. The feedback control system operates under the influence of fuel supply pressure. That is, the pressure of the fuel from the fuel tank 18 is increased by the fuel pump 19, and the pressure of the fuel is increased by the fuel pressure regulator valve 2.
1, the fuel pressure is adjusted to a predetermined value and the fuel is supplied to the fuel supply device. Fuel having a predetermined fuel pressure is supplied from the fuel supply device 201 to the supply port 33 of the underwrapped open center type pilot valve 30. The pilot valve 30 is provided with a discharge port 34, and the return pipe 23 is connected to the discharge port 34. This return pipe 23 leads directly to the fuel tank 18, so that the fuel pressure in this return pipe is approximately at atmospheric pressure. An operating pressure port 35 is provided between the fuel supply port 33 and the discharge port 34 of the pilot valve 30.
is in communication with the single acting cylinder 41. A piston 40 is introduced into the single-acting cylinder, and the piston 40 and the rotating arm of the air valve 3 are linked together. Further, the air valve 3 is provided with a spring 44 to bias the air valve in the opening direction. Note that the pilot valve 30' is a pipe 20b that is provided with a pressure chamber 48 and is branched from the fuel supply pipe 20.
Therefore, fuel pressure is applied via the fixed throttle 49. This pressure chamber 48 is configured as a fuel pressure adjustment chamber for 02 sensor feedback, and is connected to an exhaust pipe (not shown) of the internal combustion engine.
0 by the signal of the 02 sensor (not shown) attached to the
The two-sensor actuator 404 is operated to control the flow rate of fuel discharged from the pressure chamber 48 to the tank 18, thereby adjusting the pressure in the pressure chamber 48. 02 when starting the internal combustion engine
The sensor actuator 404 is operated to increase the fuel discharge flow rate so that the pressure chamber 48 is in a low pressure state, and the sensor actuator 404 is operated to increase the fuel discharge flow rate so that the pressure chamber 48 is in a low pressure state.
Since the valve 01 is moved to the left by the spring 403, the opening of the throttle valve bypass pipe 407 is controlled, which allows the internal combustion engine to start smoothly. The fast idle device is not related to the present invention and will not be described in detail. Shaft-off valve 404 is preferably of the electromagnetically operated normally closed type. Spool 3 of pilot valve 30
The left end of the shaft No. 1 is in contact with a lever 28 whose upper end is pivotally attached to a pivot ball 27, and the lower end of this lever 28 is connected to a diaphragm 26 of an intake pipe air force (intake air pressure) detection device 26a. .

This diaphragm 26 is provided with a spring 26c that is normally biased to the left. This suction air pressure detection device 26a has a diaphragm 26 on the side where the spring 26c is located.
These form a compartment 26d, which communicates with the air chamber 6 of the intake pipe 1 via a pipe 26b. With the above configuration, when the suction negative pressure in the air chamber 6 becomes high, the diaphragm 26 moves against the spring 26c of the suction air pressure detection device 26, and the lever 28 is rotated counterclockwise.

This test bar 28 presses against the spool 31 of the underwrapped open center type pilot valve 30,
Move it to the right. The operating pressure port 35 of the pilot valve 30 thus communicates with the discharge port 34 . Since the operating pressure of the cylinder 41 is reduced, the piston 40 can be retracted by the force of the spring 44. This movement of the piston 40 opens the air valve 3 and introduces a large amount of air into the suction pipe 1. Since the pressure in the air chamber 6 increases due to the introduction of a large amount of air, the diaphragm 26 of the intake air pressure detection device 26a
Returned by 6c. The trial bar 28 rotates clockwise to loosen the pressing force of the spool 31, so that the spool 31 is moved to the left by the pressure of the pressure chamber 48 and returned to its normal position. In this state, the piston 40 of the cylinder 41 is stationary and stable. Conversely, when the negative pressure of the intake air in the air chamber 6 decreases, the intake air pressure detection device 26a rotates the lever bar 28 clockwise, so the spool 31 moves to the left due to the low pressure in the pressure chamber 48, and the spool 31 moves to the left in the cylinder 41. transmits fuel supply pressure;
Move the piston 40 to the right to close the air valve 3.

When the air valve 3 is closed, the pressure in the air chamber 6 decreases, so the intake air pressure detection device 26 rotates the lever bar 28 counterclockwise to return the spool 31 of the pilot valve 30 to its normal state. By the operation of the feedback control device described above, the steady state pressure in the air chamber 6 is always kept constant at a predetermined value.

Air valve 3 is linked to fuel metering device 8a.

Preferably, the fuel metering device measures the amount of fuel supplied to the internal combustion engine in proportion to the amount of intake air. In other words, if the pressure difference before and after the fuel metering device 8a is kept constant, the opening degree of the metering orifice of the fuel metering device 8a can be made proportional to the amount of intake air.The fuel metering device 8a will be explained below. do. The fuel metering device 8a is mainly composed of an air valve 3, a fuel metering rod 8 connected by a link 7, and a sill 9 that slidably holds the fuel metering rod 8.

The fuel metering rod 8 has a hollow cylindrical end 10 located within the sill 9, and a slit 10a is provided in this end 10. This slit 10a is designed to coexist with an annular groove 12 provided in the cylinder 9. In other words, the annular groove 12 and the slit 10a constitute a metering orifice. The cylinder 9 is provided with a fuel inlet 11 that is connected to a fuel branch pipe 20, and fuel having a fuel supply pressure is sent into the cylinder 9 through the fuel inlet 11. The fed fuel enters the hollow portion of the end 10 of the fuel metering rod 8 and reaches the slit 10a. The fuel is metered and flows out into the metered fuel flow path 13 through a yield orifice with a relationship determined by the amount of overlap between the fuel slit 10a and the annular groove 12. Since the fuel metering rod 8 is connected to the air valve 3 via the link 7,
Fuel can be metered according to the movement of the air valve 3. air valve 3
In order to make the movement of
1 and the metered fuel flow path 13 must be kept constant at all times. Therefore, in the present invention, a constant differential pressure valve device with a new configuration is provided. This constant differential pressure valve device will be explained below. The constant differential pressure valve device is the fuel metering device 8
diaphragm valve device 14 that detects and amplifies fluctuations in the pressure difference across a and an injector 337 that variably throttles the metered fuel delivered to the internal combustion engine in response to the detected and amplified fluctuations in the pressure difference. It mainly consists of a built-in variable aperture device.

The diaphragm valve device 14 has a first chamber 147 having a metered fuel boat 146 adapted to be connected to the metered fuel flow path 13 and the flow path 11 .
The first chamber 147 and the second chamber 148 are connected to the diaphragm 5.
It is divided by 1.

In the second chamber 148, a nozzle 331 is arranged, which has a front end with an inlet 351 that faces the center of the diaphragm and is closed, and a rear end with a discharge boat 352. The discharge port 352 is connected to the fuel tank 1 via the flow path 507.
Lotus is suitable for 8. A fixed throttle 506 is provided in the flow path 507, and the fixed throttle 506 provides flow resistance to the discharged fuel from the discharge boat 351. Therefore, when the fuel flow rate from the discharge boat 351 increases, the discharge fuel pressure on the upstream side of the fixed throttle 506 increases accordingly. Channel 50
71 is connected to one end of the flow path 353 on the upstream side of the fixed throttle 506. The other end of this flow path 353 is the injector 3
It is connected to the pilot chamber 505 of the No. 37 variable throttle device. Note that a spring 147a is provided in the first chamber 147 of the diaphragm valve device 14 to move the diaphragm 51 into the second chamber 147.
It is biased toward chamber 148. The metered fuel channel 13 branches off into a channel 15 upstream of the diaphragm valve arrangement 14 .

The flow path 15 is connected to the metering fuel chamber 334 of the variable throttle device of the injector 337 . The pilot chamber 505 and metering fuel chamber 344 of the variable throttle device are provided by a movable piston 335.
It is divided by. A piston rod 336 is integrally provided on the movable piston 335. The piston rod 336 extends vertically through the metering fuel chamber 334 and connects the metering fuel chamber 3.
It penetrates through a pore 332 provided in the front wall of the injector 337 and enters a fuel discharge chamber 338 having a circular cross-section of the injector 337. This fuel discharge chamber 338 is connected to the piston rod 336
It is composed of a cylindrical part with the same diameter as the cylindrical part and a conical part having a nozzle opening □ 344 at the tip. The cylindrical portion of this fuel discharge chamber 338 includes a metering fuel chamber 334 and a fuel boat 339, which is fitted with a metering fuel chamber 334.
340 is closed. This fuel boat 339,340
As shown in detail in FIG. 2, the fuel boats 339,
The metered fuel discharged from 340 is rotated in the fuel discharge chamber 338 to atomize the fuel finely. That is, by adopting the configuration shown in FIG. 2, the fuel discharge chamber forms a fuel swirl chamber.The tip of the piston rod 336 forms a fuel boat 339,
The piston rod 336 and fuel boats 339 and 340 constitute a variable throttle. Fuel is ejected from the fuel discharge chamber 338 into the intake pipe 1 through the nozzle entrance 344, but since an air swirl chamber 345 is provided around the nozzle opening 344, part of the intake air flowing inside the intake pipe is is introduced into the air swirl chamber 345 from the air inlet 92 to provide a rotating air flow, so the fuel rotated in the fuel discharge chamber 346 is further rotated by this rotating air flow and becomes even more fine. Atomized fuel condition.

Note that springs 503 and 334a are provided in the metering fuel chamber 334 and the pilot chamber 505, respectively, to bias the movable piston 335 in opposite directions. . The operation of the constant differential pressure valve device will be explained below.

Fuel receiving row 1 and metering fuel flow path of fuel metering device 8a? 3
If the pressure difference between It moves toward the second chamber 148 and approaches the tip of the nozzle 331.

For this reason, the supplied fuel flowing into the introduction port 361 is throttled. Therefore, the flow rate of fuel that passes through the discharge boat 352 and returns to the fuel tank 18 from the fixed throttle 506 decreases.
The pressure in the flow path 353 drops rapidly. For this reason, the pressure in the pilot chamber 505 of the variable throttle device of the injector 337 also drops rapidly, and the movable piston 335 moves toward the pilot chamber. By this movement of the movable piston 335, the fuel boats 339, 3406 are largely closed, and the fuel in the metering fuel chamber 334 is transferred to the discharge chamber 338 of the injector 337 with small flow resistance to the fuel boats 339, 340.
Make it squirt more. The flow of less resistance lowers the pressure in the metered fuel flow path 13 so that the incremental pressure in the flow path 13 is negated and a predetermined pressure differential is maintained at the fuel metering device. Conversely, when the pressure in the metered fuel flow path 13 decreases, the diaphragm 51 of the diaphragm valve device 14 moves toward the first chamber 147 and increases the gap with the nozzle 331, so that the inlet port 3
51 increases, and the flow rate returned to the fuel tank 18 from the fixed throttle 506 through the discharge boat 352 increases.

As a result, the pressure in the flow path 353 and, therefore, in the pilot chamber 505 rises rapidly, moving the movable piston 335 toward the metering fuel chamber 334, so that the openings of the discharge boats 339, 340 are reduced and the flow from the metering fuel chamber 334 to the discharge chamber 338 is reduced. Outflowing fuel is throttled. Therefore, the pressure in the metering fuel flow path 13 increases to compensate for the reduced pressure. As described above, since the diaphragm valve device 14 and the variable throttle device of the injector 337 form an integral feedback automatic control system, the pressure difference through the fuel metering device 8a is always maintained at a predetermined value with high precision, and therefore the air At the same time, it is possible to meter fuel proportional to the movement of the valve 3, and at the same time, the diaphragm valve device 14 is different from the diaphragm of a conventional constant differential pressure valve.
The size of the diaphragm 51 can be reduced.

Furthermore, the transient response to fuel metering is stable and hunting does not occur. Although the present invention has been described above in the form of embodiments, the present invention is not limited to the above embodiments, and can be variously modified within the scope of the claims.

For example, in the above embodiment, the flow path 1 is arranged so that most of the metered fuel bypasses the diaphragm valve 14 of the constant differential pressure valve device.
3 and 15 are provided, however, the metered fuel may be configured to flow through the first chamber 147 of the diaphragm valve device 14 as shown in FIG.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing a fuel supply device for an internal combustion engine which is an embodiment of the present invention, FIG. 2 is an enlarged sectional view taken along the lo-n line in FIG. Cross-sectional view showing the main parts of the modified form. 1... Intake pipe, 3... Air pipe, 4...
...throttle valve, 8a...', fuel metering device, 14...diaphragm valve device, 18...
Fuel tank, 19...Fuel pump, 21...
・Pressure control valve, 337...injector. Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1. A metered amount of fuel is supplied to the downstream side of a throttle valve in an intake pipe of a fuel-injected internal combustion engine according to the opening degree of an air valve provided upstream of the throttle valve in the intake pipe through an injector. a fuel metering device which is a fuel supply device for injecting and is linked to the air valve; a fuel feed device which supplies fuel from the fuel tank to the fuel metering device at a predetermined pressure; a constant differential pressure valve device that maintains a pressure difference at a predetermined value; the constant differential pressure valve device includes a diaphragm valve device that detects and amplifies fluctuations in pressure difference via the fuel metering device; a variable throttle device disposed therein and operative in response to fluctuations in the amplified pressure difference, the diaphragm valve device having a first chamber for introducing fuel pressure downstream of the fuel metering device; a second chamber into which fuel pressure is introduced from the upstream side of the fuel metering device; the first chamber and the second chamber are partitioned by a diaphragm; the first chamber has a diaphragm on the second side; A first spring biasing the fuel tank is provided, and the second chamber is provided with a nozzle having a tip inlet facing the diaphragm and a rear end discharge port connected to the fuel tank via a fixed throttle. The diaphragm is displaced in response to a pressure difference across the metering device, thereby varying the flow rate of fuel flowing through the inlet port of the nozzle, thereby amplifying pressure fluctuations upstream of the fixed throttle. A fuel supply device characterized by: 2. In the fuel supply device according to claim 1, the variable throttle device includes a metering fuel chamber into which the metered fuel is introduced, a pilot chamber into which the exhaust fuel discharged from the exhaust port is introduced, and the metering fuel chamber. a movable piston that partitions the pilot chamber; a piston rod that is integrally provided with the movable piston; a second spring that is provided in the metering fuel chamber that biases the movable piston toward the pilot chamber; A fuel supply device characterized in that it has a third spring mounted on the movable piston for biasing the movable piston into the metering fuel chamber, and a variable throttle operated by the piston rod. 3. In the fuel supply device according to claim 2, the injector has a fuel discharge chamber having a nozzle opening that opens into the intake pipe, and the fuel discharge chamber has a cylindrical shape having the same diameter as the tip of the piston rod. a chamber, and two or more fuel ports are opened in the tangential direction of the cylindrical chamber, the fuel ports and the tip of the piston rod move together to constitute the variable throttle, and the metered fuel is supplied to the fuel ports. A fuel supply device characterized in that the fuel is discharged from the fuel into the discharge chamber and swirled, and the fuel is jetted into the intake pipe from the nozzle opening in the form of a mist. 4. In the fuel supply device according to claim 3, the portion of the fuel discharge chamber where the fuel port opens is a bore portion having an inner diameter approximately the same as the diameter of the piston rod, and the nozzle opening is opened from the bore portion. A fuel supply device characterized in that a conical dome portion that tapers toward the bore portion is adjacent the bore portion. 5. The fuel supply device according to claim 4, wherein the fuel port communicates with the metering fuel chamber. 6. The fuel supply device according to claim 5, wherein a plurality of the fuel ports are provided. 7. The fuel supply device according to claim 6, wherein the fuel ports are spaced apart by an angle of 180 degrees. 8. The fuel supply device according to any one of claims 1 to 7, further comprising an air swirl chamber surrounding the nozzle opening, and a plurality of air ports opening into the air swirl chamber. A fuel supply device comprising: 9. The fuel supply device according to claim 1, wherein all of the metered fuel from the fuel metering device is guided to the variable throttle device via the diaphragm valve device and the first chamber. Characteristic fuel supply device.